In conventional voice-activated systems, audio samples are monitored and processed to detect the presence of human voice activity. After human voice activity is detected, the audio samples of the human voice are further processed via speech-processing techniques. Typically, the utterance of a particular word or phrase triggers the transition of the system from monitoring for human voice activity to performing speech processing. For example, a human may utter the following: “Blue Genie, what is the temperature?” In this example, “Blue Genie” is the “trigger,” and the remainder is the “command.” Therefore, a conventional voice-activated system will monitor audio samples to detect the trigger phrase “Blue Genie.” Any word uttered by the human voice after the trigger phrase is detected is subsequently speech-processed by the voice-activated system.
One conventional implementation uses a single high-performance ADC to process all speech, including the trigger and the command. However, this implementation has numerous drawbacks. For example, designing and operating the ADC to meet the high signal-to-noise ratio (SNR) requirements at all times results in high power consumption and thus shortened battery life. In a device such as a mobile phone, voice-activated control is often not a primary means of controlling an electronic system. Thus, power consumed monitoring for uttered words provides limited benefit to the user of the mobile device.
Shortcomings mentioned here are only representative and are included simply to highlight that a need exists for improved electrical components, particularly for ADCs and speech detection in voice-activated systems employed in consumer-level devices, such as mobile phones. Embodiments described herein address certain shortcomings but not necessarily each and every one described here or known in the art.